lock up switch and sled pulling

Competition / Pulls / OffRoadYou wanted it, well you got it. The competition and pulling forum. Please have your racing, pulling and other competition posts here. No East Coast vs. West Coast, and no flame wars!

Got the local pulls coming up on the 13th, and I read that some guys are running a lock up switch. Any opinions on this, and at what point are you guys engaging it, right off the bat, when it shifts to 2nd, etc? Im pulling with the 03 in my sig.